The Islamic conquest of India is probably the bloodiest story in history. It is a discouraging tale, for its evident moral is that civilization is a precious good, whose delicate complex of order and freedom, culture and peace, can at any moment be overthrown by barbarians invading from without or multiplying within.

Will Durant, The Story of Civilization: Our Oriental Heritage page 459.

Hindustan is a country which has few pleasures to recommend it.... Indians have no idea of the charms of friendly society, of frankly mixing together, or of familiar intercourse.... They have no horses, no good grapes, or musk melons, no good fruits, no ice or cold water, no good food or bread in their bazaars, no bath or colleges, no candles, no torches, not a candle stick

There does not exist a history of ancient India. Their books contain no historical data whatever, except for a few religious books in which historical information is buried under a heap of parables and folk-lore, and their buildings and other monuments also do nothing to fill the void for the oldest among them do not go beyond the third century B.C. To discover facts about India of the ancient times is as difficult a task as the discovery of the island of Atlantis, which, according to Plato, was destroyed due to the changes of the earth... The historical phase of India began with the Muslim invasion. Muslims were India's first historians.

England's industrial supremacy owes its origin to the vast hoards of Bengal and the Karnatik being made available for her use....Before Plassey was fought and won, and before the stream of treasure began to flow to England, the industries of our country were at a very low ebb.

Sir William Digby 'Prosperous India: A Revelation,' p. 30.

...I became more than ever convinced that it was not the sword that won a place for Islam in those days in the scheme of life. It was the rigid simplicity, the utter self-effacement of the prophet, the scrupulous regard for his pledges, his intense devotion to his friends and followers, his intrepidity, his fearlessness, his absolute trust in God and his own mission. These, and not the sword carried everything before them and surmounted every trouble.

M. K. Gandhi said about the spread of Islam in the 7th century Arabia: Young India, (1924)

Islam had brought to India a luminous torch which rescued humanity from darkness at a time when old civilizations were on the decline and lofty moral ideals had got reduced to empty intellectual concepts. As in other lands, so in India too, the conquests of Islam were more widespread in the world of thought than in the world of politics. Today, also, the Muslim World is a spiritual brotherhood which is held together by community of faith in the Oneness of God and human equality. Unfortunately, the history of Islam in this country remained tied up for centuries with that of government with the result that a veil was cast over its true spirit, and its fruits and blessings were hidden from the popular eye.

N.S. Mehta, Islam and the Indian Civilization

The impact of the invaders from the north-west and of Islam on India had been considerable. It had pointed out and shone up the abuses that had crept into Hindu society - the petrification of caste, untouchability, exclusiveness carried to fantastic lengths.

[[Jawaharlal Nehru], wrote in his book Discovery of India, 1946 p. 218

History makes it clear however, that the legend of fanatical Muslim, sweeping through the world and forcing Islam at the point of sword upon conquered races is one of the most fantastically absurd myths that historians have ever repeated.

Islam at the Crossroad (1923), p. 8

From the time Muslims started arriving, around 632 AD, the history of India becomes a long, monotonous series of murders, massacres, spoliations, and destructions. It is, as usual, in the name of 'a holy war' of their faith, of their sole God, that the barbarians have destroyed civilizations, wiped out entire races. Mahmoud Ghazni was an early example of Muslim ruthlessness, burning in 1018 of the temples of Mathura, razing Kanauj to the ground and destroying the famous temple of Somnath, sacred to all Hindus. His successors were as ruthless as Ghazni: 103 temples in the holy city of Benaras were razed to the ground, its marvelous temples destroyed, its magnificent palaces wrecked.

Alain Danielou: Histoire de l' Inde

The conquering army burnt villages, devastated the land, plundered people’s wealth, took Brahmins and children and women of all classes captive, flogged with thongs of raw hide, carried a moving prison with it, and converted the prisoners into obsequious slaves.

Hindu sage Padmanabha described in his KanhaDade Prabandha in 1456 AD the story of the Muslim invasion of Gujarat of 1298 AD

(The Muslims had) enriched our culture, strengthened our administration, and brought near distant parts of the country... It (the Muslim Period) touched deeply the social life and the literature of the land.

The blood of the infidels flowed so copiously at Thanesar that the stream was discoloured, notwithstanding its purity, and people were unable to drink it. The Sultan returned with plunder which is impossible to count.

The magnitude of crimes credited to Muslim monarchs by the medieval Muslim historians, was beyond measure. With a few exceptions, Muslim kings and commanders were monsters who stopped at no crime when it came to their Hindu subjects. But what strikes as more significant is the broad pattern of those crimes. The pattern is that of a jihãd in which the ghãzîs of Islam 1) invade infidel lands; 2) massacre as many infidel men, women, and children, particularly Brahmins, as they like after winning a victory; 3) capture the survivors to be sold as slaves; 4) plunder every place and person; 5) demolish idolatrous places of worship and build mosques in their places; and 6) defile idols which are flung into public squares or made into steps leading to mosques. Still more significant is the fact that this is exactly the pattern 1) revealed by Allah in the Quran; 2) practised, perfected and prescribed by the Prophet in his own life-time; 3) followed by the pious Khalifas of Islam in the first 35 years of Islamic imperialism; 4) elaborated in the Hadis and hundreds of commentaries with meticulous attention to detail; 5) certified by the Ulama and the Sufis of Islam in all ages including our own; and 6) followed by all Muslim monarchs and chieftains who aspired for name and fame in this life, and houris and beardless boys hereafter.

Goel, S. R. (2001). The story of Islamic imperialism in India. New Delhi: Voice of India.